FT-817 Serial Interface

Even though the FT-817 is designed for portable operations, having the ability
to connect it to the main station computer has many uses. CAT and memory
management are perhaps the two main uses for such a connection.

The FT-817 can easily be controlled via a serial data connection located on the
rear of the rig. Unfortunately, the data level is not the standard RS-232
bipolar data output used by a PC serial port, so level conversion is required.

Fortunately for us, the RS-232 standard implemented in most PC serial ports is
quite forgiving in terms of applied voltage. In most cases, the serial
input data does not need to swing below zero volts to indicate a change.
This makes it very easy to convert the data stream with simple components.

This circuit is typical of the
many simple TTL/RS-232 conversion designs available. The values of the
components are not critical, so feel free to use whatever you happen to have
in your junk box. Just be careful about the 10K resistor connected
to the +13.8V. If the resistor is reduced too far in value, or if it is
shorted directly to ground, you may find yourself having to replace R1235
within the FT-817!

Since the circuit is so simple, it's quite easy to build it "dead bug"
style within a DB-25 or DB-9 connector shell. Just make sure that you
insulate all of the exposed wires from potentially shorting to ground or each
other. I accomplished this on my interface with a strip of cellophane
tape wrapped around all of the components.

I have had no problem running this interface with a standard PC serial card for
programs such as grig
and gpredict using the default 4800
baud serial speed. Running it off of a USB to serial adapter has not
always as successful, no doubt due to the limited output voltages available to
such devices.